Madonna transformed into Mudonna as she got down and dirty in a marshy stream in Italy.

The Material Mom, who’s seven months pregnant, was all smiles as she marched into the muck on the tiny island of Pantelleria.

It was the sexy pop goddess’ final vacation before she returns to London to give birth to her second child, Star magazine reports.

Madonna began her retreat earlier this month as she, boyfriend Guy Ritchie and 3-year-old daughter Lourdes arrived on the peaceful island that sits between Sicily and the African coast.

They checked into a posh seaside villa that rents for $15,000 a week.

Madonna quickly fell in love with the therapeutic mud at a nearby stream and began making daily trips to the drink.

Wearing a skimpy black bikini that showed off her ample tummy, the 41-year-old entertainer quickly turned the stream into her own personal playpen, as photos in this week’s Star and National Enquirer show.

Digging huge hunks of mud from the bottom, Madonna smeared the thick black stuff all over her body, and even painted her face with it.

Then she’d sit down, wash it off and begin all over again.

“At one point, Lourdes asked Madonna to bring some mud for her to play with. Madonna began laughing and then came charging toward her little girl teasing that she was going to ‘give you a big muddy squeeze,'” a source told Star.

“Pantelleria’s mud is legendary for giving its users a healthy glow, smoother, silkier skin and even curing acne.”

But it wasn’t all fun and games for the blonde chart-topper, who had a recent No. 1 smash with “American Pie.”

When she wasn’t playing piggy-in-the-sty, Madonna was busy bicycling up and down the island’s steep hills.

After her second child – reportedly a boy – is born, she plans to take a break from singing and acting to be a full-time mom.